diff --git a/gpu-vulkan-middle.cabal b/gpu-vulkan-middle.cabal
--- a/gpu-vulkan-middle.cabal
+++ b/gpu-vulkan-middle.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           gpu-vulkan-middle
-version:        0.1.0.54
+version:        0.1.0.55
 synopsis:       Medium wrapper for Vulkan API
 description:    Please see the README on GitHub at <https://github.com/YoshikuniJujo/gpu-vulkan-middle#readme>
 category:       GPU
diff --git a/src/Gpu/Vulkan/Memory/Middle.hs b/src/Gpu/Vulkan/Memory/Middle.hs
--- a/src/Gpu/Vulkan/Memory/Middle.hs
+++ b/src/Gpu/Vulkan/Memory/Middle.hs
@@ -20,7 +20,7 @@
 
 	-- * MEMORY TYPE
 
-	MType(..), TypeBits, TypeIndex, elemTypeIndex ) where
+	MType(..), TypeBits, TypeIndex, elemTypeIndex, Heap(..) ) where
 
 import Prelude hiding (map, lookup)
 import Gpu.Vulkan.Memory.Middle.Internal
diff --git a/src/Gpu/Vulkan/Memory/Middle/Internal.hsc b/src/Gpu/Vulkan/Memory/Middle/Internal.hsc
--- a/src/Gpu/Vulkan/Memory/Middle/Internal.hsc
+++ b/src/Gpu/Vulkan/Memory/Middle/Internal.hsc
@@ -18,7 +18,7 @@
 	Requirements(..), requirementsFromCore,
 	Barrier(..), barrierToCore,
 
-	Heap, heapFromCore,
+	Heap(..), heapFromCore,
 
 	MType(..), mTypeFromCore,
 	TypeBits, TypeIndex, elemTypeIndex, typeBitsToTypeIndices